Polycarbonate is a well known thermoplastic having excellent properties with respect to impact resistance, electrical conductivity and thermal stability, among others. Various blends of polycarbonate with other polymers and additives have been made to upgrade the properties of polycarbonate. Often times however, various properties of polycarbonate need not be upgraded but merely held within the usual range while other properties of the polycarbonate may have to be reduced in order to qualify for certain applications.
One particular property of polycarbonate is that a molded article has a glossy exterior. However for many applications of polycarbonate it is preferred and indeed specified in some instances that the exterior of certain objects, for example, business machines have a dull as opposed to glossy appearance. Additionally certain properties such as the distortion temperature under load, usually abbreviated as DTUL, be reduced instead of maintained at its relatively high point of 130.degree. C. A lower distortion temperature under load should bring about an easier processing polymer so as to more readily make more intricate shapes and thinner sections. Additionally for many of these applications, there need not be as high an impact resistance as polycarbonate would normally have. Other properties which may be upgraded in the polycarbonate for the particular application include the hydrolytic stability, ultraviolet stability and the flame retardance. Particularly for internal usage in a business environment, the thin hulls of a business machine should be rendered flame retardant.
Therefore it is desirable to obtain a polycarbonate based composition wherein the gloss of the composition is substantially below that of polycarbonate alone, the DTUL is substantially lower than polycarbonate while maintaining a significant amount of the 3.2 mm Notched Izod impact resistance of the polycarbonate and upgrading the flame retardance of the thinnest section, 1.6 mm thick test sample.
It has now been discovered that specific compositions of polycarbonate together with other polymers and additives bring about this unusual group of properties.